1. Field of the Invention
This invention relates to a reel receiving device including a friction coupling member which transmits a turning force of a motor to a reel receiving body by way of a frictional transmitting mechanism and operates, for example, an automatic reversing mechanism or an automatic stopping mechanism in response to rotation or stopping of the reel receiving member.
2. Description of the Prior Art
A reel receiving device in a tape recorder includes, for example, as shown in FIG. 2, a reel receiving body 3 as a main component which is mounted for rotation on a reel shaft 2 erected on a base 1 and is prevented from being pulled off the reel shaft 2 by means of a stopper (for example, an E-snap ring) 4 fitted at an end portion of the reel shaft 2.
The reel receiving body 3 includes a cylindrical member 6 having a flange 5 at a lower end thereof, a cap 7 press-fitted on an upper end portion of the cylindrical member 6, and a reel driving member 8 fitted for axial movement along an outer periphery of the cap 7. The reel driving member 8 has a plurality of (in normal cases, 3) engaging projections 8a for engagement with a tape reel (not shown) in a rotational direction and is normally urged upwardly (toward the end of the reel shaft 2) from below by means of a first spring member 9.
A gear 10 is mounted for rotation around an outer periphery of the cylindrical member 6 above the flange 5. The first spring member 9 is interposed between an upper surface of the gear 10 and the reel driving member 8. The gear 10 is driven to rotate by a turning force transmitted thereto from a motor (not shown) by way of a rotation transmission mechanism 20.
Meanwhile, a friction coupling member 11 is mounted for rotation on and relative to the reel shaft 2 between the flange 5 and the base 1. The friction coupling member 11 has a disk portion 12 and an arm portion 13 extending from an outer periphery of the disk portion 12 thereof. The arm portion 13 of the friction coupling member 11 engages with a mechanism 14 such as, for example, an automatic reversing mechanism or an automatic stopping mecahanism, which operates in response to rotation or stopping of the reel receiving body 3.
Friction members 15, 16 each in the form of a sheet such as, for example, a felt sheet, are interposed between the flange 5 and the gear 10 and between the flange 5 and the disk portion 12 of the friction coupling member 11. A second spring member 17 is interposed between the gear 10 and the cap 7 and urges the gear 10 to press against the flange 5 of the cylindrical member 6 via the friction member 15 in order to allow rotation of the gear 10 to be frictionally transmitted to the flange 5. The friction member 5, the second spring member 17 and the associated surfaces of the flange 5 and the gear 10 constitute a friction transmission mechanism 19 for transmitting a turning force applied to the gear 10 to the reel receiving body 3.
A third spring member 18 is interposed between the disk portion 12 of the friction coupling member 11 and the base 1 and normally urges the disk portion 12 toward the flange 5 via the friction member 16 in order to allow a turning force of the flange 5 to be frictionally transmitted to the disk portion 12 via the friction member 16. By this construction, a pressing force is applied to the friction coupling member 11 in response to rotation or stopping of the reel receiving body 3. However, since the friction coupling member 11 is held from rotation by the mechanism 14 with which the arm portion 13 thereof engages, the disk portion 12 thereof will produce a pressing force against the mechanism 14 in a direction of rotation thereof while yielding a slip between the disk portion 12 and the friction member 16.
If a tape reel (not shown) is loaded on the reel receiving device having such a construction as described above, that is, on the reel driving member 8 thereof and a turning force of the motor is transmitted to the gear 10 by way of the rotation transmission mechanism 20, the gear 10 is rotated thereby, and such rotation of the gear 10 is transmitted to the reel receiving body 3 by way of the friction transmission mechanism 19 to drive the tape reel to rotate.
Then, if a tape wound on the tape reel comes to its end, rotation of the reel receiving body 3 is stopped, yielding a slip between the gear 10 and the friction member 15. Consequently, the pressing force of the friction coupling member 11 against the mechanism 14 disappears so that, where the mechanism 14 is an automatic reversing mechanism, the feeding direction of the tape will be switched reversely. Meanwhile, where the mechanism 14 is otherwise an automatic stopping mechanism, the tape recorder will be stopped.
By the way, the first spring member 9 on one hand assists the second spring member 17 in providing a press contacting force between the gear 10 and the friction member 15 and on the other hand by itself urges the reel driving member 8 upwardly. Accordingly, if a reel hub is contacted with the top end of an engaging projection 8a of the real driving member 8 when a tape reel is loaded, the reel driving member 8 will be moved down once and then moved up back to its initial position to fit with the reel hub when the reel hub is disengaged from the engaging projection 8a after starting of rotation of the reel receiving body 3. Accordingly, the first spring member 9 is required to have a very low axial elastic force.
To the contrary, the second spring member 7 is required to have a significantly high axial elastic force because it must provide a sufficient press contacting force between the gear 10 and the friction member 15.
Meanwhile, the axial elastic force of the third spring member 18 need not be very high because it must only transmit information of whether the reel receiving body 3 is rotating or not as presence or absence of a pressing force of the friction transmission member 11 against the mechanism 14.
In summary, preferably the elastic forces of the first and third spring members 9 and 18 are low while the elastic force of the second spring member 17 is high.
However, as apparent from the structure described above, the first and second spring members 9 and 17 and the third spring member 18 press the gear 10, the flange 5 and the friction coupling member 11 toward each other from above and below. Accordingly, unless the third spring member 18 has an elastic force sufficient to defeat a composite pressing force of the first and second spring members 9 and 17, the reel receiving body 3 will move down or sink, causing a disadvantage that the reel driving member 8 and the gear 10, and in addition, the friction coupling member 11 will not be held to respective fixed vertical positions. Therefore, the elastic force of the second spring member 17 cannot be very high, and consequently, it is a problem that it is difficult to provide a sufficient press contacting force between the gear 10 and the friction member 15.
It is another disadvantage that a contact resistance appearing between the third spring member 18 and the base 1 checks an action of the friction coupling member 11 to follow the reel receiving body 3. This disadvantage may possibly cause a trouble, for example, that a sufficient pressing force is not applied to the mechanism 14 by the friction coupling member 11 while the reel receiving body 3 is rotating. This will cause operation in error of the mechanism 14 so that, for example, the feeding direction of a tape may be inadvertently switched reversely or the tape recorder may be stopped.